1. Field of the Invention
This invention relates to the field of analytical devices where analytes are filtered and bound to a membrane and the membrane is then analyzed for the presence of analyte.
2. Description of the Prior Art
The prior art describes a wide variety of filtering devices ranging from filter paper to individual test units which involve binding specific binding substances such as antibodies and antigens to porous filter membranes as described in U.S. Pat. No. 4,642,285. U.S. Pat. Nos. 4,703,353; 4,591,550; 4,758,786 and 4,704,353 and references therein disclose a photoresponsive electrode generally adaptable to measurements made in the present invention. U.S. Ser. No. 065,418 filed Jun. 18, 1987 assigned to the same assignee as this application discloses a Zero Volume Electrochemical Cell where analytes on porous filter membranes are measured by means of a photoresponsive electrode. U.S. Ser. No. 258,894 assigned to the same assignee as this invention, is directed to Hapten Derivatized Capture Membranes useful as membranes for the slides of this invention.
References of interest include U.S. Pat. Nos. 4,020,830 to Jense, et al.; 3,975,238 to Bean, et al.; 4,238,757 to Schenck; 4,486,272 to Fujihira, 4,293,310 to Weber; and 4,444,892 to Malmros; and International Patent Publications Nos. WO83/02669 and WO85/04018. See also "Experimental Electrochemistry for Electrochemists," Sawyer and Roberts, Wiley-Interscience, pp. 350-353.
U.S. patents of interest also include U.S. Pat. Nos. 4,168,146, which concerns a test strip for immunoassays, where the extend to which an analyte travels is related to the amount of analyte in the medium; 4,298,688, which involves a three-zone strip, where the extent of travel of an enzymatic product is determinative of the amount of glucose analyte; 4,299,916, which concerns an assay technique employing a support for detection of the analyte; 4,361,537, which employs strips in conjunction with RIAs; 4,366,241, which concerns employing a small test zone for concentrating a particular component of the assay medium in a small area; 4,435,504, which concerns an immunochromatograph employing channeling; 4,442,204, which concerns using homogeneous assay reagents on solid support where displacement of labeled conjugate-analyte complex by analyte provides the desired signal; 4,533,629, which employs a simultaneous calibration technique for heterogenous immunoassays; 4,446,232, which employs a solid support having a zone occupied by labeled conjugate, followed by receptor, where binding of analyte to the labeled conjugate allows the labeled conjugate to traverse the receptor zone to a detection zone; 4,447,526, which employs a homogenous specific bonding assay system in conjunction with carrier matrix; and 4,454,094, which involves displaced apart layers through which a medium traverses, where reagent from one layer diffuses to the other layer in relation to the amount of analyte in the medium.